Sound-propagating diaphragm



Dec. 30, 1930. M. n. HuTcHlsoN 1,787,003

' sounn PROPAGATING DIAPHRAGI Filed May 2, 153s Patented Dec. `30, 1930 .UNITED ASTATES, PATENT OFFICE MILLER EEEsE HUTGHIsoNgoF L'LEWELYN rAEK, WEST ORANGE, NEW JERSEY, As- Y SIGNOR 1, PREMIER LABORATORY COMPANY, A CORPORATION OF DELAWARE l SOUND-PROPAGATING DIAPHRAGM Application led May 2, 1928. Serial No. 274,527.

The invention relates toa sound propagating apparatus for the propagation of low rfrequency sound waves. One of ythe objects of theinvention is to provide va sound' propagating apparatus which will be of small size relative to the y .length of the sound waves which it may propagate. y 'y Another object of the invention is to provide a sound propagatingA diaphragm of lsmall dimensions which may effect the production of sound waves of the lower portion of the musical' register; Y

A further object of theinvention is that of furnishing a reproducer which, in operation, will result in pleasing acoustical impressions 'in that theA reproduced sound waves will cover, with marked purity and brilliance, the entire range. which is to be reproduced and, lfurthermore in that, by means of the present l invention the two series of sound waves propagated by the opposite diaphragm faces will not acoustically interfere with each other. l i A' still further feature is that of providing an 1 improved coupling between the dia phragm and actuating member bf the reproducer.V .Y n

Other objects and features will appear from the following description in connection 3@ with the accompanying drawings in which y Figure lis a perspective view of areproducer; 'A

` Figure 2 shows a reproducen# :the diaphragm of which embodies a Construction different from thatillustrated in Figure l, this diaphragm alsobeing positioned dierently from the positioning of the diaphragm of Figure l and e Figure 3 shows a clutch which may be 4o employed to couple thediaphragm with the actuating unit. y

In the following description andl claim, parts, characteristic features and functions 4 will be identified by specific means for convenience of expression, but they are intended to be as generic in theirapplication to similar parts or equivalent construction as the arty Y will permit. 4

` In these views the numeral 5 indicates a su cabinet of any desired configuration which,

in the present instance, mounts a casing rectangular in cross-section. This casing thus embracestop andV bottom walls 6 and 7 and sidewalls 8, the unobstructed ends `of the casing extending into, or being inline with, openings formed in the walls of the cabinet 5.

At this time it is to be understood that the cross-sectional configurationV of the casing, while preferably rectangular, may have any "other desired shape, and, furthermore, that lt'need not ynecessarily be mounted in a cabinet. Also, these parts may be manufactured of any desirable material consistent with the reproduction and Arpropagation of sound waves of high quality.

\ f As shown in Figure lwhere, as aforesta'ted,

a rectangular casing isy employed, a diaphragm 9 is positioned intermediate the ends of the casing to'fill the entire passa-ge thereof. Thispositioning may be achieved as, for example, by forming the'inner casing face with va groove and `having the diaphragm ofsuficient area to extend into this groove to'provide, -virtually or actually, an air-tight connection ,betweenl these elements. A

Thediaphragm shown in Figure lmay be formed of any desirable material and is of such comparative area that it will serve, nor- `mally, to propagate sound, waves of the mid- -dle or upper portion of the musical register.

However, dueto the-fact that the diaphragm is connected by means'ofan air-tight joint to'the casing, the two endsof thellatter are virtually' isolated. Consequently, columns ofair exist to both sides of the diaphragm andare defined by the casing. These .col-

umns of atmosphericfmedium"will be inert and as aiconsequence, when the diaphragm vibrates, their inertia willgact upon this ele- `ment, resulting in a damping ofthe diaphragm from its natural period of vibration toa slower vibrational frequency. Thus, as

aforestated, although the diaphragm is preferably Lof sucharea kthat it would tend to V- propagate, primarily, sound waves of the middle or up'perportion of theV musical register, it will be apparent that, by means of the vdamping effect aforestated, it will likewise propagate iny a ysatisfactory l manner sound waves of the lower portion of the musical register.

It will also follow, as a result of having the diaphragm disposed within a casing, the ends of which face in different directions and Which ends are comparatively remote from each other, ythat the sound waves propagated by the opposite diaphragm faces will be directed in different directions and will not intermingle until such time as the sound waves have expanded in the atmospheric medium exteriorly of. the reproducer to an extent whereby their ensemble effect will not produce a conflicting impression upon the ear of a. person. This will obviously be true, due, as aforestated, to the propagation of the two trains of sound waves in different directions and the guiding influences thereon exerted by the casing, particularly if the same `is relatively long, and will furthermore be true irrespective of the area of the diaphragm.

If desired, as shown in Figure 2, the diaphragm may be positioned adjacent one end of the chamber or casing. Under such circumstances it will be obvious that sound waves propagated by what might be termed the outer diaphragm face will pass immediately to the atmospheric medium beyond the casing. However, the sound waves propagated by the opposite face of the diaphragm are caused to pass through the entire length of the casing and to be thus guided in a definite direction, whereby conflicting interminglement of the two trains or series .of sound waves is prevented. It is also obvious that by this construction the damping effect of the ponderous semiconfined atmospheric medium of the chambers will not be equal and the effects thereof on the faces of the diaphragm will be correspondingly different.

Furthermore, as shown in Figure 2, it will be apparent that, if desired, the diaphragm may be of composite formation and include a pair of spaced facing sheets 10 between which there is interposed a corrugated sheet 11 to provide air cells between the sheets 10. All of these sheets may be formed of paper or similar fibrous material and a sizing, or coating of material, may be applied to the outer face of one of the facing sheets 10 to provide a layer 12, whereby the weight and texture of the two facing sheetsis different. Thus, variations in the character of the sound waves propagated by the opposite faces of the diaphragm will follow.

In the structure of both of these views the diaphragm is vibrated in any desired manner as, for example, by an electromagnetic unit 13 from which an operating stem or arm 14 eX- tends. Irrespective of the mode of actuation of this stem or arm, it may be coupled to the diaphragm conveniently by the use ofthe clutch. mechanism shown in Figure 3. In this view it will be seen that a disk 15 is suitably attached to the diaphragm face and has an outwardly dished portion 16 formed with an opening through which a collar member 17 extends. This member has flanges by means of which play between the disk and its body is prevented and this member, furthermore, has a screw-threaded split stem 18, the threads of which are engaged by a tapered nut 19. rIhus, the arm 14 is passed through the bore of the nut and into the stem, and when the parts have been properly correlated the nut is tightened until the chuck provided by the stem 18 frictionally engages the arm 14 to such an extent that play between these parts is prevented. Thus a convenient attaching structure is provided which, while readily uncoupled, will permit of the parts being adjusted when necessary and which, upon the parts being so adjusted will maintain the same free from play therebetween.

The invention upon which this application is based is broader than the specific embodiment shown and described for the purpose of illustrating at least one of the ways in which it may be employed. 'Ihe scope of the invention is therefore to be understood as not being limited by the present specific descripr tion. I intend no limitations other than those imposed by the claim.

What is claimed is:

A sound propagating apparatus compris- Ving a diaphragm, means for damping the vibrations of said diaphragm formed of a plurality of spaced fiber sheets comprising a chamber surrounding said diaphragm in such a manner as to subject the diaphragm to the retarding influence of the inertia of the atmospheric medium within said chainber.

Signed at New York in the county of New York and State of New York this 17 day of January A. D. 1928.

MILLER REESE HUTCHISON. 

